CN1189175C - Novel compsns. and methods for prevention and treatment of protozoal disease - Google Patents

Abstract

The present invention provides a composition that has been specially adapted for parenteral administration, e.g., intranasal, intramuscular, subcutaneous, transdermal or intraveneous administration, wherein the composition is comprised of at least one anti-protozoal drug in a therapeutically effective amount for the treatment or prevention of protozoan infections in man an in animals. In one embodiment, the anti-protozoal drug is a triazine-based anticoccidial agent, e.g., a triazinedione or triazinetrione such as diclazuril, toltrazuril, sulfonotoltrazuril or water-soluble sodium salts thereof. In a presently preferred embodiment, the triazine-based anticoccidial agent is sulfonototrazuril. Methods of treatment of protozoal infections in man and animals are also provided in the present invention.

Description

Compositions and methods for preventing and treating protozoan diseases

This application claims priority to US Provisional Application Serial No. 60/103,543, filed October 8, 1998, and US Provisional Application Serial No. 60/112,175, filed December 14, 1998.

Field of Invention

The present invention relates to methods of treatment and prevention of diseases caused by protozoan parasites in humans and animals. In particular, the present invention relates to novel compositions and methods for the parenteral treatment and prevention of protozoan diseases such as pirplasmosis, babesiosis, Neospora caninum toxoplasmosis, Cryptosporidium Crytosporidiosis and equine encephalomyelitis.

Background of the Invention

Protozoan parasites (also known as apicoplexan parasites) cause different clinical disease manifestations in humans and animals. For example, blood protozoan parasites of the genus Babesia, Babesia caballi and Babesia equi, cause the economically devastating disease horse piroplasmosis. Pyoplasmosis is widespread worldwide, however, it is most prevalent in tropical, subtropical, and temperate regions (see RobinsonEdward N. Current Therapy In Equine Medicine Vol 2 pp 299-300( 1987) (ISBN: 0-7216-1491-4)).

The main mode of transmission of the protozoa is via tick vectors such as Ophthalmophthora clematis. The clinical presentation of acute infection is characterized by depression, fever, anorexia, jaundice of the mucous membranes, hemorrhagic ecchymosis, and edema of the extremities and abdomen. Death can occur within 24-48 hours and the mortality rate during attacks is high (see Robinson Edward N. "Current Therapy In Equine Medicine" (Current Therapy In Equine Medicine) Vol. 3 pp. 499-500 (1992) (ISBN: 0- 7216-3475-3)).

Horses that test positive for pirsiplasmosis (complement fixation test or indirect fluorescent antibody test) are not allowed into the United States without treatment for the disease or under strict guidelines (see Brooks, L. "Piroplasmosis: The Olympic Question", The Horse) pp. 43-48 (July 1996). Current suggested treatment regimens include the use of medocaine dipropionate (Burroughs Welcome Co.) and this treatment often produces adverse side effects including salivation, restlessness, and gastrointestinal hypermotility (see Kobluk, Calvin N. et al. Diseases and Clinical Control" (The Horse Diseases & Clinical Management) Vol. 2 pp. 1084-1885 (1995) (ISBN: Vol. 2 0-7216-5984-5)). Furthermore, especially when the causative agent is Babesia equi, treatment with midocarp dipropionate has been decisively successful (50%-60%) (see Reed, Stephen M. Equine Internal Medicine) pp. 570-571 (1998) (ISBN: 0-7216-3524-5)).

Accordingly, there is a need in the art for effective antiprotozoal agents and methods of treating and preventing pirsiplasmosis that do not produce the adverse side effects observed with current treatment regimens.

Other examples of protozoal infections in the blood caused by Babesia species include: bovine babesiosis, such as Babesia disjoint and Babesia bovis; goat and ovine babesiosis, such as ovine Babesia and canine babesiosis, eg, Babesia canis and Babesia gibsonii (see Smith, Bradford P. Large Animal Internal Medicine pp. 1088-1092 (1990) (ISBN: 0-8016-5062-3)), see also Bonagura, John D. "Kirk's Current Veterinary Therapy XII Small Animal Practice" (Kirk's Current Veterinary Therapy XII Small Animal Practice) Vol. 12 pp. 315-319 (1995) ( ISBN: 0-7216-5188-7). Also, there is a need in the art for safe, effective and economical treatments for such infections.

For example, in humans, protozoal infections can lead to severe disease manifestations. A common sequel in patients with acquired immunodeficiency syndrome (AIDS) is Cryptosporidium parvum infection (cryptosporidiosis) producing severe chronic and often fatal diarrhea. The parasite is found to be widespread worldwide and lives in cattle and domestic animals and is excreted in feces. It can be transmitted directly to humans from animals or through contact with feces, contaminated water, or food (see, for example, "Allergic and Infectious Diseases—Cryptosporidiosis Associated with AIDS" National Institute of Allergy and Infectious Diseases-AIDS-related Cryptosporidiosis), online release (www pressrelease) (March 1991).

Many attempts have been made to find an effective treatment for this disease. Triazine-based anticoccidials (such as triazinediones and triazinetriones), especially digrams, have been experimentally attempted to be used in the field of veterinary medicine for the treatment of this type of coccidiosis. Zuril and letrazizumab are used to treat cryptosporidiosis in humans (see National Library of Medicine AIDS DRUGS database (National Library of Medicine, AIDSDRUGS Database) DRG-0079 (January 22, 1998) and National Drug Library AIDSSTRIALS database ( National Library of Medicine, AIDS STRIALS Database) FDA-038B (April 25, 1990). These compounds have been formulated for oral administration and they have had limited success due to poor absorption. The best response to this class of drugs has been observed in humans by the highest blood levels following administration (see AIDS Treatment News No. 111 (September 21, 1991)).

However, to date, there is still no effective therapy for Cryptosporidium infection in humans (see Health Canada, Laboratory Center For Disease Control: Material Safety Sheet)- 48. Cryptosporidum parvum, October 11, 1997 @ ( www.hc-sc.gc.ca/hpb/lcdc/biosaty/msds/msds/48e.html (July 24, 1999)). Therefore, in this There remains an urgent need in the art for safe and effective parenteral formulations for the treatment and prevention of protozoan infections such as cryptosporidiosis or babesiosis.

Equine protozoal encephalomyelitis (EPM), a disease of the central nervous system that affects equine species, is also primarily caused by the protozoan parasite Sarcocystis neuroma, also known as Sarcocystis falcatula. Horses are not a normal host for this protozoa (horses are not part of the normal life cycle) and it is considered an end-of-mortem host. The decisive host is considered to be the opossum. Equines become infected with the S. neuroma organism through ingestion of food or water contaminated with the feces of infected carnivorous organisms such as possums (see RobinsonEdward N. Current Therapy In Equine Medicine: Fenger, Clara A "Equine Protozoal Myeloencephalitis" Vol. 4 pp. 329-333 (1997) (ISBN: 0-7216-2633-5)).

More recently, other protozoan parasites have also played a causative role in the pathogenesis of EPM, such as Neospora caninum and Toxoplasma species. Therefore, there remains a need in the art for an effective therapy for EPM that exhibits broad-spectrum efficacy against all protozoan parasites in horses, including the above-mentioned organisms.

The clinical signs of EPM can vary from case to case. In general, horses present with asymmetrical neurotic symptoms and actual symptoms vary with the severity and location of damage produced by the parasite in the brain, brainstem or spinal cord. Ataxia, incoordination, and general weakness are usually present and may be accompanied by muscle wasting (often most notably in the hind limbs). There may be eye and facial muscle paralysis, drooping ears, difficulty swallowing (dysphagia), head tilt, changes in gait, and even seizures and collapse. Recent reports of the number of EPM cases suggest that the disease is far more widespread and severe than originally thought.

There is currently no vaccine available to prevent this disease. The currently preferred method of treatment is aimed at the control of parasitic infections through the application of sulfonamides and pyrimethamine (see US Patent No. 5,747,476). However, these established methods have met with limited success. More recently, and because of the urgent need for safe and effective treatments for this devastating disease, new treatments have been explored and researched, for example through the FDA's emergency import of antiprotozoals such as diclazuril and toltrazuril. New agents (see FDACVM Publication: "Instructions for Personal Use Importation of Diclazuril" (December 16, 1997); and FDACVM Publication: "Importation of Personal Use Importation of Diclazuril" ( The Introduction of Toltrazuril for Personal Use) (1997) from the American Association of Equine Practitioners, Lexington, KY (AAEP)). (See also US Patent No. 5,883,095).

It should be noted that the current emergency import of diclazuril and toltrazuril and the treatment of horses with diclazuril and toltrazuril are exploratory. Oral formulations of one or more of these drugs for use in horses are currently in clinical trials for FDA approval. And while some horses did improve significantly, many saw only moderate improvements (1-2 on the clinical rating scale (scale range 1-5) used by veterinarians to classify the severity of clinical signs). level improvement). The current preferred form of toltrazuril, the metabolite toltrazuril sulfone (Bayer), tested for FDA trials is currently tested at doses ranging from 5 mg/kg/day to 10 mg/kg/day.

The cost of the above mentioned antiprotozoal imports and their application ranges from about $800-$1,200.00/horse anywhere and the results obtained from this treatment can be dismal. Few horses experienced complete recovery from any of the known conventional therapies including the triazine-based antiprotozoal regimens described above. Furthermore, the relatively high doses of drugs suggested in this regimen can produce unwanted side effects. This is especially true for regimens using sulfonamides and pyrimethamine, which inhibit folate production (see Fenger, ClaraA. "Update On the Diagnosis of Equine Protozoal Myeloencephalitis" - ACVIm Forum Proc. ^13th ACVIM Forum, pp. 597-600 (1995); and Bertone, Joseph J. "Update On Equine Protozoal Myeloencephalitis," FDA Veterinary Volume XI, III period (May/June 1996)).

Therefore, there is a need in the art to provide a safe and more effective parenteral treatment of EPM at a lower cost.

Summary of the invention

The present invention fulfills this need in the art by providing a composition for the treatment and prophylaxis of protozoal infections in humans and animals which is particularly suitable for parenteral administration, wherein said composition contains at least one For antiprotozoal drugs, the parenteral administration is, for example, intranasal, intramuscular, subcutaneous, transdermal or intravenous administration. In one embodiment, the anti-protozoal drug is a triazine-based anti-protozoal drug, eg triazinedione or triazinetrione such as diclazuril or toltrazuril. In a presently preferred embodiment, the triazine-based anticoccidial is sulfonotoltrazuril.

The compositions of the present invention may further comprise suitable solvents for the antiprotozoal drug in formulations particularly suitable for a particular route of parenteral administration. Of course, the choice of solvent and the concentration of active agent dissolved therein depends on the choice of drug, the desired route of parenteral administration, the species and host to be treated and the desired duration of action of the administration e.g. vary.

Parenteral administration of the composition of the present invention is reduced to about 1/2 to 1/100, and especially to about 1/5 of the drug dose for oral administration. The composition provided by the present invention eliminates the variability of the plasma concentration of the drug due to differences in oral bioavailability from animal to animal, can apply a loading dose and thereby immediately achieve an effective plasma concentration of the drug, and quickly achieve a high plasma concentration of the drug Rather, accessing the drug to extravascular compartments such as the cerbrospinal fluid in the CNS provides better and more rapid control of the plasma concentration of the drug and reduces the potential for side effects associated with existing oral formulations. The result is a significant reduction in the cost of treatment and the potential for adverse side effects, as observed from the higher doses currently recommended and required for oral administration of these antiprotozoal drugs.

In particular, the present invention provides novel agents for the treatment and/or prophylaxis of any antiprotozoal or apicoplexan parasites such as equine plasmosis, equine encephalomyelitis and cryptosporidiosis in humans and animals. Compositions and methods. In one embodiment, the present invention provides a composition comprising a triazine-based antiprotozoal drug and a suitable solvent for use in antiprotozoal infection therapy. A preferred embodiment of the invention comprises a composition consisting of diclazuril dissolved in DMSO, DMA or a mixture thereof formulated for parenteral administration to humans and animals provided by the methods of the invention In vivo antiprotozoal therapy.

Another preferred embodiment of the present invention comprises a composition consisting of toltrazuril, toltrazuril sulfone, sulfonotoltrazuril or mixtures thereof dissolved in DMSO, DMA or mixtures thereof formulated for parenteral administration Form for antiprotozoal infection therapy in humans and animals provided by the method of the present invention.

Another preferred embodiment of the present invention comprises a composition formulated for parenteral or oral administration for the treatment of antiprotozoal infections in humans and animals, which consists of a triazine-based antiprotozoal drug such as carat Zuril, diclazuril, letrazuril, toltrazuril, toltrazuril sulfone or sulfonotoltrazuril (sulfonotoltrazuril) and other water-soluble salts such as sodium salt composition.

The present invention further provides a method for preparing a water-soluble dosage form of a triazine-based anti-protozoal drug used in the anti-protozoal infection therapy provided by the present invention, and the triazine-based anti-protozoal drug is, for example, carat Zuril, diclazuril, letrazuril, toltrazuril, toltrazuril sulfone, or toltrazuril sulfonyl.

                    Invention Details

The present invention provides a composition and method for the parenteral treatment of protozoan (apicoplexan) infections in humans and animals. The protozoan parasite can be any protozoa known to infect humans and animals, including but not limited to: e.g. Babesia species, Sarcocystis species, Neosporum species, Cryptosporidium species, Toxoplasma species types etc.

It is contemplated that the compositions of the present invention can be formulated for any parenteral administration. Of particular interest are intravenous, intramuscular, transdermal, intranasal and subcutaneous routes of administration that can be used to administer the compositions of the invention. Particular formulations of compositions of the invention include powders, gels, ointments, creams, solutions, suspensions, sustained release formulations, patches, and the like.

In one embodiment, the present invention provides a composition particularly suitable for intravenous, intramuscular, subcutaneous or intranasal administration for the treatment of protozoal infections in humans and animals, said protozoal infections in humans and animals For example, infection with horse pyoplasmosis, equine encephalomyelitis or human cryptosporidiosis; wherein said composition includes at least one chemically active agent having antiprotozoal activity. The compositions provided herein include any anticoccidial drug, and in particular an anticcidial drug such as any type of triazine-based anticoccidial drug (i.e., containing a triazine ring such as a 1, 2, 4 triazine ring or 1 , 3, 5 triazine ring configurations (see, for example, "3D-QSAR studies of antiprotozoal triazines using molecular speciation analysis" - "J.Chem.Inf.Computer Science Information" (J.Chem.Inf.Computer .Sci.) Vol. 35 771-778 (1995); US Patent No. 4,837,216 and US Patent No. 4,952,570, the contents of which are incorporated herein by reference)).

Specific examples of such active agents include, but are not limited to, clazuril, diclazuril, letrazuril, toltrazuril, toltrazuril sulfone, or sulfonotoltrazuril. For example, the chemical structures of several triazine-based compounds useful in the compositions and methods described herein are shown below:

克拉珠利

Krajuli

地克珠利

Diclazuril

来曲珠利

Letrazuril

Toltrazuril

It is understood that other antiprotozoal agents, including their derivatives, analogs, isomers, salts and natural metabolites of these active agents, may also be used in the parenteral treatment and prophylaxis of any protozoal infection in humans and animals. composition. In a presently preferred embodiment, the triazine-based anticoccidial is sulfonotoltrazuril, a metabolite of toltrazuril.

Toltrazuril sulfonyl (toltrazuril metabolite) contains the sulfur group of toltrazuril that has been oxidized to a sulfonyl group, thereby distinguishing it from its dioxysulfonyl toltrazuril derivatives.

Toltrazuril Sulfonyl Toltrazuril

The chemical name for one form of sulfotoltrazuril used in the Chemical Abstracts database to which this invention is concerned is:

1-methyl-3-[3-methyl-4-(4-trifluoromethanesulfonyl-phenoxy)-phenyl]-[1,3,5]triazinane-2,4,6- Triketones.

The CAS catalog number for this compound is CAS No. 69004-04-2. Beilstein accession number 870959. The molecular formula is C ₁₈ H ₁₄ F ₃ N ₃ O ₆ S and the molecular weight is 457.38 g/mol.

In particular, the present invention provides a composition for parenterally treating and/or preventing EPM, which uses about 1/4 to about 1/100 of the amount of antigen necessary for oral administration during the treatment of EPM Insect medicine. In one embodiment of the invention, said composition is suitable for intranasal administration and comprises about 1/10 the currently recommended dosage. In another embodiment, the composition is suitable for other modes of parenteral administration (e.g., intravenous, subcutaneous, and intramuscular) and comprises about 1/4 to about 1/100 of the currently recommended oral dose, and In particular about 1/3 to about 1/10 of the currently recommended oral doses for EPM therapy. In a preferred embodiment, the above-described intranasal and parenteral compositions of the present invention are formulated for sustained release as described in more detail below.

For example, the current recommended dose of oral diclazuril (CLINACOX®, Pharmacea Upjohn, Canada) for an in vivo EPM regimen in horses is about 2.5 grams of diclazuril per 1000 pounds of horses per day (5.5 mg/kg), Dosing once a day for 28 days. This is equivalent to about 70 grams of diclazuril/horse/treatment regimen.

In contrast, the currently preferred dosage range for parenteral compositions of the invention consisting of similar triazine-based active agents such as diclazuril or toltrazuril for the treatment of EPM is about 0.1 mg/day. kg - about 10 mg/kg. However, those skilled in the art will understand that this range can be between about 0.01 mg/kg and about 20 mg/kg depending on the particular formulation, route of administration, desired effect (loading dose versus sustained release) and duration of the treatment regimen. change between.

The presently preferred embodiment of the present invention comprises a composition suitable for parenteral administration comprising an anti-protozoal drug selected from but not limited to clazuril, diclazuril and a suitable solvent The group consisting of toltrazuril, letrazuril, toltrazuril, toltrazuril sulfone and sulfonyltrazuril or its sodium salt. The solvent may be any suitable solvent for use in animals and humans and will of course vary with the antiprotozoal drug chosen and the route of administration. Presently preferred solvents include, but are not limited to, DMSO, DMA, ethanol, water, and the like as more fully enumerated below.

Preferred compositions can be used in the therapy of antiprotozoal infections in humans and animals. For example, a currently preferred treatment regimen for the treatment of EPM comprises the step of administering to 1000 lb horses an intravenously administered composition consisting of about 50 mg to about 1,500 mg of , and especially from about 250 mg to about 1000 mg and most preferably about 500 mg (about 1.1 mg/kg) of diclazuril, toltrazuril, toltrazuril sulfone or sulfonyltrazuril. A suitable amount of solvent may vary from about 2ml to about 30ml per unit dose, depending on the antiprotozoal drug chosen and the solvent chosen. According to the methods described herein, the composition (SID) may be administered once daily for a period of about 10 days to about 35 days, especially about 20 days to about 30 days and most preferably about 28 days. Alternatively, a loading dose of the composition may be given to achieve a rapid critical plasma concentration on day 1 of the regimen, followed by maintenance of the dose (see Example 1 below) for a shorter treatment period, for example about 15- About 25 days.

In another embodiment, the composition, such as microspheres or methylcellulose formulations, may be formulated especially for parenteral applications, such as intramuscular or subcutaneous, sustained release, such that a single sustained release administration or each Weekly sustained release formulations of antiprotozoal drugs are possible. On the other hand, a single intravenous loading dose followed by a slow-release intramuscular or subcutaneous dose to maintain sustained critical plasma levels is of interest. For example, in EPM, the critical plasma concentration may be in the range of about 5 μg/ml antiprotozoal to about 12 μg/ml antiprotozoal, and especially about 8 μg/ml.

Example of Intravenous Administration

Example #1

  Single IV administration of "MR.OWENS" and diclazuril:

                                         

Concentration (ng/ml) Time (days)

As described in Table 1 above, horse MR.OWENS (approximately 1,000 lbs) received twice 750 mg of diclazuril powder dissolved in 30 ml of DMSO intravenously at hours 0 and 0+1 on day 1 for a total dose of 1,500mg. Blood samples were taken at the indicated time points immediately before the next dose and the solid circles (•-•) in Figure 1 represent plasma concentrations of diclazuril after these doses. Plasma concentrations of diclazuril in ng/ml are listed on the vertical axis and the corresponding time in days is listed on the horizontal axis. Note: The peak plasma concentration of diclazuril of 6,000 ng/ml at 24 hours post-dose and the plasma half-life of approximately 48 hours are consistent with previously reported data on the plasma half-life of diclazuril in horses.

Example #2

Repeat daily IV dosing of "DEEP POWDER" and diclazuril:

                                                                    

Concentration (ng/ml) Time (days)

Diclazuril (580 mg) dissolved in DMSO was intravenously administered once a day to horse DEEP POWDER (1160 lbs) in Table 2 above at a dose of 0.5 mg/lb for 8 days. The solid circles (•-•) in Table 2 above represent the plasma concentrations of diclazuril at 24 hours after each administration and just before the administration on day 2. Note how the dose of 580 mg/1,000 lbs/day produces stepwise increasing plasma concentrations of diclazuril, resulting in a final steady state plasma concentration of diclazuril of approximately 10,000 ng/ml. Also note the exhaustive comparison between these data and pre-submitted data for CLINICOX(R), where approximately 2.5 g/1,000 lbs of diclazuril administered orally daily as CLINICOX(R) produced broadly similar data. The data show that IV administration of approximately 0.5 mg/1,000 lbs of diclazuril dissolved in DMSO produces plasma concentrations of diclazuril that are equivalent to plasma concentrations of CLINICOX® administered orally at approximately 5 times this dose, suggesting this activity The oral bioavailability of the agent is about 20% or less.

Example #3

"Loading dose" effects and predicted beneficial effects of treatment:

                                       

Concentration (ng/ml) Time (days)

Pharmacokinetics and additive mechanisms suggest that administration of a loading dose such as that described in Example 1 (MR OWENS) followed by daily maintenance of a dose such as that described in Example 2 (DEEP POWDER) should be rapidly achieved and maintained Desired or optimal therapeutic plasma concentration of diclazuril (approximately 8-10 μg/ml plasma). Table 3 above shows that if a loading dose of 1,500 mg is given on day 1, followed by a daily maintenance dose of 500 mg of DEEP POWDER, estimated plasma concentrations can be obtained in horses with approximately 1,000 lb body weight of MR.OWENS and DEEP POWDER . In this way, total effective plasma concentrations of diclazuril or related active agents can be rapidly achieved on day 1 of treatment and maintained for any desired period of time, according to these general protocols and mechanisms.

The advantages of this approach are manifold: in the first aspect, effective plasma and cerebrospinal fluid concentrations of diclazuril or a similar active agent can be reached within hours or minutes of initiation of treatment, which allows for a shorter duration of treatment. In a second aspect, based on our dosing experiments with CLINICOX®, the desired plasma concentration can be maintained by administering only about 1/5 or less of the total drug dose that must be given orally, which can The drug cost is basically saved. Thirdly, the significant variability in the horse-to-horse bioavailability of this active agent and the variability in the resulting plasma concentrations of diclazuril found after oral administration can be avoided, thereby making the therapeutic outcome more accurate. predictable and reproducible. In the fourth aspect, using this method can quickly reach a very high plasma concentration of diclazuril, so that diclazuril can also quickly enter the CNS and act as an antiprotozoal drug in the CNS. The fifth aspect is to finally establish the optimal plasma concentration and optimal treatment period of diclazuril for the treatment of this disease and most of the low-cost treatment means for EPM.

This IV method of administering diclazuril provides an essential means of obtaining this information for precise control of the plasma concentration of the drug and the cerebrospinal fluid concentration of the active agent through precise control of the drug concentration and rapid entry of the drug into the CNS. The sixth aspect and the final fact that IV administration exposes the horse to lesser amounts of the drug via the direct enteral route and no exposure to any drug reduces the likelihood of the development of adverse reactions involving the horse's gastrointestinal system and other body systems .

Example #4

MR.OWENS/CLINACOX data: pharmacokinetic analysis and bioavailability calculation:

Concentration (ng/ml) Time (hour)

Pharmacokinetic analysis of the data obtained after IV administration of the drug and comparison with previously reported pharmacokinetic data after administration of CLINACOX® (Table 4 above) indicates that the estimated oral bioavailability of CLINACOX® It was actually 20 percent lower than an earlier estimate. In Table 2, the intravenous data from MR.OWENS (filled squares - - ) are plotted together with pre-obtained CLINACOX® oral dosing data (filled circles - - ) and pharmacokinetics as described below analyze. These data suggest that the bioavailability of orally administered CLINACOX(R) is approximately 13% or less of that shown in the figure described in the above experiments.

Example #4

MR.OWENS/CLINACOX DATA: PHARMACOKINETIC ANALYSIS AND BIOAVAILABILITY CALCULATION /Continued:

The concentration of diclazuril at 120 hours after oral administration was considered as an outlier.

Area under the curve (AUC from 0-∞): The trapezoidal rule was used to calculate the area under the curve for oral drug dosing.

$\mathrm{<span\; class="notranslate">\; AUC</span>}{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; =</span>\frac{\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; +</span>\mathrm{<span\; class="notranslate">\; C</span>}\mathrm{<span\; class="notranslate">\; 2</span>}}{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 1</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; t</span>}}_{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; )</span>$

Primary reaction: $k=\frac{\ln C_1-\ln C_2}{t_1-t_2}$ k = 0.0164 hours ^-1

0-∞ AUC(PO)＝98.2μg/ml/hour

Concentrations at 72 hours and 96 hours after IV administration were not included in the calculation.

k＝0.021小时^-1 Area under the curve (0-∞ AUC): Intercept-Slope method

k = 0.021 hours ^-1

AUC (0-∞ AUC) (IV): 452.4 μg/ml/hour

F=13%

V=0.35L/kg

Cl = 55.26ml/min.

The fact that diclazuril concentrations were not detectable in urine samples by HPLC and TLC suggests that hepatic clearance is the major route of elimination for diclazuril in horses. Cl _H ＝ Q _H .E _H

With EH below 0.3, it was found that diclazuril has a low proportion of hepatic excretion.

In another preferred embodiment of the present invention, the above-mentioned preferred composition can be used for antiprotozoal infection therapy in animals other than EPM. For example, a presently preferred treatment regimen for the treatment of piroplasma in horses comprises the step of administering to a 1000 lb horse a composition for intravenous administration consisting of about 50 mg to about 1,500 mg, especially about 250 mg - about 1000 mg and most preferably about 500 mg (about 1.1 mg/kg) of diclazuril, toltrazuril, toltrazuril sulfone or sulfonytortrazuril dissolved in a suitable volume of DMSO, DMA or the like. A suitable amount of solvent may vary from about 2ml to about 30ml per unit dose, depending on the antiprotozoal drug chosen and the solvent chosen. According to the methods described herein, the composition (SID) may be administered once daily for a period of about 1 day to about 20 days, and especially about 1 day to about 10 days and most preferably about 4 days. Alternatively, a loading dose of the composition may be administered to rapidly achieve critical plasma concentrations on day 1 of the regimen, followed by maintenance of the dose for a shorter therapeutic period, eg, from about 2 days to about 10 days. In another embodiment, the composition may particularly be formulated as a sustained release dosage form as described below to enable single administration of an antiprotozoal drug or on the other hand a single intravenous loading dose followed by intramuscular or subcutaneous administration of sustained critical blood levels of dose.

As mentioned above, clazuril, diclazuril, letrazuril, toltrazuril, toltrazuril sulfone, and sulfonyltrazuril, as well as other triazine-based antiprotozoal agents, are used for prophylaxis and Treatment of equine encephalomyelitis (EPM) and other protozoan diseases in humans and animals. These compounds are hydrophobic and very poorly soluble in water.

Prior to the teachings described herein, there were no suitable water-soluble formulations for parenteral administration of these active agents. Accordingly, the present invention provides compositions consisting of at least one antiprotozoal drug in water-soluble form for the treatment of protozoal infections in humans and animals and methods for the preparation of such compositions. In a currently preferred embodiment, the composition is composed of sodium salts of one or more triazine-based anti-protozoal drugs, including but not limited to clarazuril, diclazuril , letrazuril, toltrazuril, toltrazuril sulfone, toltrazuril sulfonyl, or a mixture thereof.

The presently preferred means for increasing the water solubility of such drugs is to prepare their salt forms. Clazuril, diclazuril, letrazuril, toltrazuril, toltrazuril sulfone, and sulfonyltrazuril are weak acids due to the presence of imine hydrogen in all five compounds shown below kind. When this hydrogen is abstracted, the anion formed is resonance stable. Thus, these acidic compounds can be reacted with a base in a typical acid-base titration reaction to form the corresponding salt and water. For example, the sodium salt of diclazuril is formed by reacting diclazuril with sodium hydroxide in a 1:1 molar ratio as described below.

Synthesis of diclazuril sodium salt

Proof of salt formation:

1. The molar ratio of sodium hydroxide required for the competitive titration of diclazuril is 1:1.

2. The salts are immediately soluble in water, whereas diclazuril is completely insoluble in water.

3. Diclazuril is a white powder. The sodium salt of diclazuril is brown in color.

4. Perform mass spectrometric analysis of diclazuril sodium salt anion form and diclazuril itself. The molecular anion of the salt and the parent compound have a predicted molecular weight of 404.971. The determined molecular weight was exactly in agreement with the predicted molecular weight (data not shown).

Thus, clazuril, diclazuril, toltrazuril, toltrazuril sulfone, and sulfonyltrazuril, as well as other triazine-based anticoccidials, generally contain an acidic imidium hydrogen, which makes it compatible with The acid-base titration reaction of a base produces the corresponding salt and water. This was demonstrated by the synthesis of the sodium salt of diclazuril described more fully in Example 5 below. With the teachings provided herein, it will be appreciated that other strong bases including, but not limited to, Ca(OH) ₂ , KOH, LiOH can also be used.

Example 5

Synthesis of water-soluble salt of diclazuril

Diclazuril has very low water solubility (<1 x 10 ^-7 at pH 6.5) and in fact it can be considered almost insoluble in water. The preferred plasma drug concentration currently required for effective treatment of equine encephalomyelitis (EPM) is about 8 μg/ml for about 25-30 days. The oral bioavailability of diclazuril is very low. Therefore, there is a need for parenteral formulations.

One of the approaches to increase the water solubility of a poorly water-soluble drug is to prepare a water-soluble salt of the drug. Diclazuril can be considered a weak acid due to the presence of the imine hydrogen as follows:

The structure of diclazuril with the acidic imine hydrogen indicated by the arrow

When an acidic hydrogen is abstracted, the anion formed is stabilized by the following resonance:

Resonance Structure of Diclazurimide Anion

Since diclazuril is a weak acid, it can be reacted with a base to form a salt and water. NaOH was chosen as the presently preferred base and an acid-base reaction was performed in which 1 gram of diclazuril was suspended in 50 ml of ethanol in a 200 ml volumetric flask. A phenolphthalein indicator is added to the system to indicate the equivalence point of the titration. Fill the burette with 1M NaOH. Base was slowly added to the solution from a burette. The titration was terminated when a color change (colorless to pink) of the phenolphthalein indicator was observed. At the equivalence point, it was observed that the milky white suspension of diclazuril had changed into a clear pink solution. This is believed to be the result of the conversion of the acid to the salt. The solution was recrystallized by evaporation in an oven set at 75°C for 2 hours.

Synthesis of diclazuril sodium salt

Calculation of the molar amount of NaOH required to titrate 1 mole of diclazuril showed a molar ratio of 1:1, suggesting an acid-base reaction and thus salt formation.

Nitrile and imine functions can be hydrolyzed by base when possible. However, it probably does not happen because the hydrolysis of nitriles and imines requires more stringent conditions including reflux for several hours. In addition, the reaction is performed in ethanol, thereby removing the water required for the hydrolysis reaction.

Proof of salt formation

1. The titration experiments strongly suggest an acid-base reaction.

2. Mass spectrometric proof: Fourier transform matrix-assisted laser desorption ionization mass spectrometry (MALDI-FTMS) using 1,8,9-thracenol matrix was used to determine diclazuril raw material and obtained from diclazuril Mass spectrum of the sodium salt of diclazuril free acid. The predicted molecular weight of diclazuril anion (C ₁₇ H ₈ C ₁₃ N ₄ O ₂ ^- ) is 404.972. The measured molecular weight was 404.971. Isotopic peaks due to chlorine were determined at m/z 406.967 and 408.965. A series of peaks at the molecular weight of 333.971 in the spectrum correspond to the fragmentation peaks of molecular ions formed after the loss of two chlorine atoms. The sodium salt was converted to the free acid by extraction with ethyl acetate and treatment with acetic acid prior to mass spectrometry. Furthermore, the predicted molecular weight of the diclazuril anion was 404.972, while the measured molecular weight was 404.971, which coincided with the predicted molecular weight. Isotopic peaks mainly derived from chlorine were also determined. An additional cluster of peaks observed at 333.971 corresponds to the fragmentation peaks obtained after the loss of two chloride ions. An additional cluster of peaks at molecular weight 395.952 not observed in the mass spectrum of diclazuril original material was observed in the mass spectrum of diclazuril free acid obtained from the sodium salt. This peak was considered to be a fragment peak of an unidentified molecular ion, a peak resulting from an impurity or a small by-product of a titration reaction. Further analysis by HPLC ensured that this peak was identified as a fragment product or an impurity.

pH Stability of Diclazuril Sodium Salt

Diclazuril's producer JANSEEN Research Foundation (JANSEEN Research Foundation) lists the pKa of diclazuril as 5.92 in terms of the physical and chemical properties of diclazuril. Aqueous solutions of diclazuril are expected to remain stable in solution at pH values above the pKa of the compound (ie, pH > 6). Preliminary studies were carried out to determine the pH at which sodium salts precipitate.

Dissolve the sodium salt of diclazuril in water. It goes into solution almost immediately. The pH of this aqueous solution was 12.4. To this solution was added 1N HCl dropwise while stirring and the pH at which the solution started to become cloudy was recorded. The pH was found to be 10.5. This shows that the pKa of diclazuril is not 5.92 as confirmed by JANSEEN, but it is closer to 10.5. Indeed, examination of reference values for the pKa of organic compounds shows that imines have a pKa in the range of 8.3-9.6.

The results of the pH stability study indicated that aqueous formulations of diclazuril sodium salt must preferably be formulated at a higher pH close to 11 in order to ensure that the drug remains stable in solution. It does not pose a problem when there are many drugs on the market that are indeed formulated at higher pH for the same reason.

Accordingly, the present invention provides a composition for the treatment of protozoal infections in humans and animals, which composition consists of a water-soluble form of a triazine-based anti-protozoal drug, said anti-protozoal drug including but Not limited to clazuril, diclazuril, tortrazuril, toltrazuril sulfone, and sulfonyltrazuril. In a currently preferred embodiment of the present invention, the triazine-based water-soluble antiprotozoal drug is clazuril, diclazuril, toltrazuril, toltrazuril sulfone, sulfonyl toltrazuril or Sodium salt of its mixture.

Preferred compositions of the present invention may be used in the therapy of antiprotozoal infections in humans and animals. For example, a currently preferred treatment regimen for the treatment of EPM comprises the step of administering to a 1000 lb horse a composition for intravenous administration consisting of about 50 mg to about 1,500 mg, especially about 250 mg to about 1000 mg And most preferably about 500 mg (about 1.1 mg/kg) of diclazuril, toltrazuril, toltrazuril sulfone or sulfonyl toltrazuril water-soluble sodium salt composition, these drugs are dissolved in An appropriate volume of sterile water or stored in a lyophilized preparation mixed with an appropriate amount of sterile water for injection at the time of use. A suitable amount of water for the composition may vary from about 2ml to about 30ml per unit dose, depending on the antiprotozoal drug chosen and the parenteral route of administration.

According to the method for the treatment of EPM described herein, described composition (SID) can be given once a day, continue about 10 days - about 35 days, and especially about 20 days - about 30 days and most preferably about 28 days the term. Alternatively, loading doses of the composition may be administered to rapidly achieve critical plasma concentrations on day 1 of the regimen, followed by maintenance of the dose for a shorter therapeutic period (see Example 1 above), for example from about 15 days to about 25 days .

Of particular further interest is the use of the triazine-based water-soluble forms of anticoctocids provided herein in suitable oral formulations for the treatment and prevention of protozoal infections and infestations in humans and animals. The solubility of the compositions provided herein significantly facilitates the oral bioavailability of the active antiprotozoal drug and thus substantially reduces the dosage requirements for parenteral formulations. Given the teachings provided herein, one skilled in the art can optimize dosage requirements and treatment regimens for particular formulations, depending upon the disease condition and species of animal being treated or prevented.

One embodiment of the present invention provides a composition, especially for the treatment of infection by Cryptosporidium spp. in humans or animals, consisting of a triazine-based antiprotozoal in water-soluble form, The antiprotozoal drugs include but not limited to clazuril, diclazuril, toltrazuril, toltrazuril sulfone or sulfonyl toltrazuril. In a currently preferred embodiment of the present invention, the triazine-based water-soluble antiprotozoal drug is clazuril, diclazuril, toltrazuril, toltrazuril sulfone, sulfonyl toltrazuril or The sodium salt of its mixture and it can be used parenterally or orally in a therapeutic regimen. It is of further interest that the above-mentioned compositions consisting of a triazine-based antiprotozoal drug and a suitable solvent such as DMSO or DMA can be used parenterally for the treatment of Cryptosporidium species infections in humans or animals.

For example, a currently preferred treatment regimen for treating Cryptosporidium spp. infection comprises administering about 10 mg to about 400 mg, especially about 25 mg to about 300 mg and most preferably about 200 mg (about 1.1 mg/ kg) of diclazuril, toltrazuril, toltrazuril sulfone or the water-soluble sodium salt of sulfonyl toltrazuril, these drugs are dissolved in a suitable volume of water or stored in the application In a lyophilized preparation mixed with an appropriate amount of sterile water for injection. Suitable amounts of water for the composition may vary from about 2ml to about 10ml per unit dose, depending on the antiprotozoal drug chosen and the chosen route of administration. It will of course be understood that oral formulations of water soluble salts of these active agents may be in liquid, semi-solid or solid dosage forms such as pills, tablets, elixirs and the like.

Current recommendations for the use of pyrimethamine and sulfonamides for EPM are described in the above-cited articles by Drs Clara Fenger (1995) and Dr Joe Bertone, which are incorporated herein by reference. Therefore, in another embodiment of the invention, the composition consists of at least one antiprotozoal drug as described above and it may also include reduced amounts of sulfonamides and/or pyrimethamine.

Those skilled in the art will appreciate that depending on the compound selected as a therapeutic agent, the methods of solubilization of the compounds contained in the compositions provided herein may vary and can be found, for example, in the Specific Compound Material Safety Data Sheet (MSDS). The selected compounds are based on known chemical properties or are conveniently determined by known synthetic methods and the like. In particular, methods for the solubilization of active compounds and formulations particularly suitable for intranasal administration are well known, as described in U.S. Pat. refer to.

Based on the combined results of EPM cases treated by the oral route to date, it is particularly surprising that better results can be obtained by using a different route of administration (i.e. intranasal) and lowering the dose, especially when the use must be performed in horses. This is especially true when it comes to antiprotozoals where organic tissues do their job. Furthermore, although the above-mentioned proposed solubilization techniques are well known, it has not been suggested so far that such techniques can be used to solubilize triazine-based An antiprotozoal drug to form a composition for intranasal administration. The intranasal route requires the drug to be absorbed directly through the nasal mucosa and directly across the blood-brain barrier into the CSF without the necessary first-pass hepatic effect. This could lead to the surprisingly better results observed with this route of administration, even with significantly lower drug unit doses.

For example, one embodiment of the invention employs a composition suitable for intranasal administration for the treatment of EPM consisting of a therapeutically effective amount of toltrazuril, toltrazuril sulfone, or sulfonyltoltrazuril wherein the unit dosage is lower than that required for a therapeutic amount of toltrazuril, toltrazuril sulfone or sulfonytortrazuril if oral administration of the respective drug would normally be required. In a preferred embodiment, the therapeutically effective amount of the composition consisting of toltrazuril, toltrazuril sulfone or sulfonyltortrazuril is about the amount of toltrazuril, tortrazuril required for oral administration. 1/4-1/100 of the therapeutically effective amount of sulfone or sulfotltrazuril, while the therapeutically effective amount of toltrazuril, toltrazuril sulfone, or sulfotltrazuril is especially required for oral administration About 1/10 of the amount. The current recommended oral dose level of toltrazuril, toltrazuril sulfone, or sulfonytortrazuril is 5-10 mg/kg/unit dose administered orally once daily, such that a typical 500 kg horse receives approximately 2.5-approx. 5 g of active ingredient.

A preferred embodiment of the present invention therefore comprises a composition consisting of toltrazuril, toltrazuril sulfone or sulfonyltrazuril dissolved in N-methyl-glucosamine and water. For example, a typical example of how to solubilize toltrazuril for use in a composition contemplated by the present invention is to mix about 10 mg of toltrazuril with about 100 mg of N-methyl-glucamine and about 10 cc of water. It will be appreciated that other solvents may be used in the preparation of the above compositions due to the known properties of toltrazuril, toltrazuril sulfone or sulfonyltortrazuril.

In one embodiment of the present invention, the effective amount of toltrazuril, toltrazuril sulfone or sulfonytortrazuril per unit dose for intranasal administration is about 50 mg to about 1,500 mg, and especially It is about 100 mg to about 750 mg. In one embodiment, the effective amount of toltrazuril, toltrazuril sulfone or sulfonyltrazuril is about 500 mg per unit dose. Depending on the dose required for the treatment or prevention of EPM (which can be optimized using methods known in the art), an appropriate amount of toltrazuril or sulfonyltrazuril can be solubilized to produce a unit dose or can be The unit doses are combined in multi-treatment vials or containers.

Likewise, another embodiment of the present invention provides a composition suitable for intranasal administration consisting of a therapeutically effective amount of diclazuril, wherein said unit dose is lower than that required for oral administration for the treatment of EPM. A unit dose of the therapeutic amount of diclazuril required. In a preferred embodiment, the therapeutically effective amount of the composition consisting of diclazuril is about 1/4-1/100 of the therapeutic amount of diclazuril required for oral administration, and especially for oral administration Approximately 1/10 of the therapeutic amount of diclazuril required.

A typical example of solubilizing diclazuril for use in a composition contemplated by the present invention is to mix about 10 mg of diclazuril with about 20 mg of niacinamide, about 300 mg of propylene glycol, and about 9-10 cc of water. It is contemplated that other solvents may be used to prepare diclazuril-containing compositions. Those skilled in the art can select from known solvents to conform to a particular embodiment, see, e.g., Janssen Pharmaceutica Safety Information for Diclazuril (R-64433), the contents of which are incorporated herein This article is for reference.

In one embodiment of the present invention, the effective amount of diclazuril per unit dose for intranasal administration is about 50 mg to about 1,000 mg, and especially about 100 mg to about 750 mg. In one embodiment, the effective amount of diclazuril is about 350 mg per unit dose. Depending on the dose required for the treatment or prevention of EPM (which can be optimized using methods known in the art), the appropriate amount of diclazuril can thus be solubilized to produce a unit dose or can be presented in multi-treatment vials or The form of the container incorporates the unit dose.

Accordingly, another embodiment of the present invention thus provides a composition suitable for intranasal administration consisting of a therapeutically effective amount of diclazuril and DMSO, wherein said unit dose is lower than that for oral administration. Unit dose of the therapeutic amount of diclazuril required to treat EPM. In a preferred embodiment, the therapeutically effective amount of the composition consisting of diclazuril and DMSO is about 1/4-1/100 of the therapeutic amount of diclazuril required for oral administration, and especially for oral administration About 1/10 of the therapeutic amount of diclazuril required for the drug.

A presently preferred embodiment of the invention comprises a composition suitable for intranasal administration comprising diclazuril dissolved in DMSO. Diclazuril is placed in DMSO solution and can be further formulated for intranasal administration with other pharmaceutically acceptable carriers and excipients to suit a particular treatment regimen. Typical unit doses for administration are from about 50 mg to about 750 mg, and especially from about 100 mg to about 500 mg, and preferably about 250 mg. In one example, 500 mg of diclazuril is dissolved in 10-15 cc of DMSO and can be used for intranasal administration. This same composition can also be used for intravenous administration in the treatment of EPM by the methods provided herein.

In general, equine subjects can be treated on a daily basis by intranasally administering the solutions, eg, catheters and syringes, which apply the solutions directly to the nasal mucosa. Depending on the quality of the animal, appropriate restraints such as a nasal depressor should be used prior to performing this procedure. After the animal is properly restrained, the catheter is advanced to the extent of the animal's nares to the oropharynx. Most of the solution is injected through the catheter on the nasal mucosa in the oropharynx, and the remainder is injected through the catheter as it is slowly withdrawn. For daily dosing, the nostril can be selected to minimize mucosal irritation if certain methods of treatment provided herein are used. The total volume of the composition administered intranasally will generally not exceed 15-20 cc per administration and preferably will not exceed about 10 cc per administration.

Thus, as described in more detail below, the above-described solution of diclazuril and DMSO may further be adapted for sustained release of diclazuril by any of a number of methods known in the art, including the use of diclazuril made of, for example, sucrose. Excipients and controlled release systems composed of isobutyrate acetate, methylcellulose or microparticles. Of course, the frequency of administration and the amount per unit dose of the sustained release compositions described herein will vary with the delivery system and the release characteristics of the particular formulation. However, optimization of dosage and treatment regimens will be routine to those skilled in the art given the teachings of the present invention.

Another embodiment of the present invention comprises a composition suitable for intranasal administration for the treatment of EPM, which composition consists of a therapeutically effective amount of the antiprotozoal drug nitazoxanide, wherein said unit dose is lower than that of oral The unit dose required for the therapeutic amount of nitazoxanide normally required is administered (as described in the references cited above). In a preferred embodiment, the therapeutically effective amount of the composition consisting of nitazoxanide is about 1/4-1/100 of the therapeutically effective amount of nitazoxanide required for oral administration, and especially for oral administration about 1/10 of the therapeutically effective amount of nitazoxanide required for the drug.

It is understood that other nitrothiazoles, their derivatives, analogs, isomers, salts and natural metabolites may also be used in the compositions disclosed herein for the treatment and prevention of EPM.

The dosage of nitazoxanide may vary from about 100 mg to about 1,500 mg depending on the particular formulation, and especially for intranasal formulations from about 250 mg to about 1000 mg.

Another embodiment of the present invention provides a composition suitable for intranasal or other parenteral administration to horses, the composition consisting of a therapeutically effective amount of pyrimethamine and at least one sulfonamide, wherein said A unit dose that is lower than the therapeutic amount of the same combination drug administered orally or otherwise parenterally for the treatment of EPM. In a preferred embodiment, the therapeutically effective amount of the combination of pyrimethamine and said sulfonamide is about 1/4-4 that of the same combination drug required for oral or other parenteral administration. 1/100, and especially about 1/10 of the therapeutic amount required for oral or other parenteral administration of the same drug combination. Of course, these compositions may contain more than one sulfonamide and pyrimethamine as well as additional pharmaceutically acceptable excipients and adjuvants.

Of additional interest are compositions suitable for parenteral (e.g. intramuscular, subcutaneous or intravenous) administration, which consist of a therapeutically effective amount of at least one chemically active agent having antiprotozoal activity, e.g. based on triazines Antiprotozoal drugs (triazinedione or triazinetrione, such as diclazuril, toltrazuril or sulfonyltortrazuril) or nitrothiazole derivatives, wherein the unit dose is lower than that for oral administration A unit dose of a therapeutically effective amount of a chemically active agent required to treat or prevent EPM. In a preferred embodiment, the therapeutically effective amount of the composition consisting of said antiprotozoal drug is about 1/4-1/100 of the therapeutic amount of the compound required for oral administration, and especially for oral administration. about 1/10 of the therapeutic amount of the compound.

The invention also provides methods for treating and preventing EPM in an equine animal (eg, a horse) comprising the step of intranasally administering a composition such as those provided by the invention. Unit dosages and treatment regimens can be fully optimized using methods generally known to those skilled in the art.

The present invention further provides methods for treating and preventing EPM in an equine animal (e.g., a horse) comprising parenterally, e.g., subcutaneously, intramuscularly, intravenously or transdermally administering a compound such as that provided by the present invention. steps of those compositions. Unit dosages and treatment regimens can be fully optimized using methods generally known to those skilled in the art.

In another embodiment of the present invention, any antiprotozoal drug disclosed herein and especially a triazine-based antiprotozoal compound or including but not limited to diclazuril, toltrazuril or toltrazuril can be used Nitrothiazoles including sulfone, sulfonetortrazuril and nitazoxanide are made into compositions suitable for sustained release. The sustained release composition may include any of a number of controlled release systems formulated for injection or absorption, such as microparticles (microspheres or microcapsules), gels, and the like. The sustained release composition of the present invention may be administered orally or by any oral or parenteral route including intramuscular, subcutaneous or intravenous injection. Also, the sustained release composition may be adapted for transmucosal or percutaneous release by patch, topical application, intranasal or intrauterine release, and the like.

The materials used to prepare microspheres or microcapsules (microparticles) may comprise any biocompatible and preferably biodegradable polymers, copolymers or blends. Suitable polymers include polyhydroxy acids, polyorthoesters, polyactones, polycarbonates, polyphosphazenes, polysaccharides, proteins, polyanhydrides, copolymers thereof, and its blends. Suitable poly(hydroxy acids) include polyglycolic acid (PGA), polylactic acid (PLA) and copolymers thereof. The microparticles preferably comprise poly(D,L-lactic acid) and/or poly(D,L-lactic-glycolic acid). Particles with degradation and release times ranging from days to weeks or months can be designed and produced based on factors such as the material used to prepare the microparticles. Of course, the sustained release compositions of interest may be used in methods of treating or preventing EPM.

The microparticles can be prepared using available methods which do not destroy the activity of the active compound. Microparticles can be prepared using single and double emulsion solvent evaporation, spray drying, solvent extraction, solvent evaporation, phase separation, simple and complex coacervation, interfacial polymerization, and other methods well known to those skilled in the art.

Methods developed for the preparation of drug-releasing microspheres are described in the literature, for example, in Microcapsules and Nanoparticles in Medicine and Pharmacy, edited by Doubrow, M., CRC Press, Boca Raton , 1992 described in . See also US Patent Nos. 5,407,609 and 5,654,008, the teachings of which are incorporated herein by reference for methods of making microspheres.

A specific example of a preferred embodiment of the controlled release system of the present invention is a combination of any of the therapeutic agents described above (including any of the triazine-based anticoccidials and/or nitazoxanide) and in U.S. Patent No. 5,747,058. The composition composed of sucrose acetate isobutyrate (SAIB), the content of this document is incorporated herein as a reference. Depending on the formulation, the composition consisting of an antiprotozoal drug and SAIB can be administered topically (eg transdermally or transmucosally), subcutaneously or intramuscularly.

Another specific example of a controlled release formulation encompassed by the present invention is a formulation consisting of any of the above therapeutic agents (including any triazine-based anticoctocid and/or nitazoxanide) and methylcellulose (e.g. Methocel ) composition. It will be appreciated that other controlled release formulations including other degradable or non-degradable excipients may be used, although degradable excipients are preferred. Depending on the formulation, the composition consisting of an antiprotozoal drug and Methocel can be administered topically (eg transdermally or transmucosally), subcutaneously or intramuscularly.

In addition, the present invention provides compositions of the above for use in the method of treatment and prevention of another common thoroughbred horse problem, a disease of unknown etiology known as sore throat. While not wishing to be bound by theory, it is believed that laryngitis may be caused by or exacerbated by EPM. Laryngeal paralysis is a paralysis of the abductor muscles that open the arytenoid cartilages of the throat due to damage to the laryngeal nerve. The arytenoid cartilage fails to open the airway and causes an infested horse to make a "growling" sound during training and the horse is short of breath. Thus, sore throat and other diseases and conditions that may be associated with EPM can be treated or prevented according to the present invention.

Additional objects, advantages and other novel features of the present invention are partly described in this specification and will be apparent to those skilled in the art from the experiments described above or can be learned by practicing the present invention.

The foregoing description of preferred embodiments of the invention has been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention in the precise form disclosed. Obvious modifications or variations are possible in light of the above teachings. Embodiments were chosen and described in order to provide the best explanation of the mechanism of the invention and its practical application to enable those skilled in the art to use the invention in various embodiment forms and in various modified form as appropriate to the particular application concerned . All such modifications and changes are within the scope of the present invention as determined by the appended claims when interpreted in accordance with the breadth to which they are properly, legally and equitably entitled.

Claims (9)

1. Use of sodium salts of triazine-based anti-protozoal drugs for the preparation of drugs in the form of oral administration for the treatment or prevention of protozoan infections in humans or animals, wherein the triazine-based anti-protozoal drugs are selected from The group consisting of clazuril, diclazuril, letrazuril, toltrazuril, toltrazuril sulfonyl, toltrazuril sulfone and mixtures thereof. 2. The use of claim 1, wherein said triazine-based antiprotozoal drug is selected from the group consisting of clazuril, diclazuril, letrazuril, toltrazuril and mixtures thereof. 3. The use of claim 1, wherein said triazine-based antiprotozoal drug is sulfonyl toltrazuril or toltrazuril sulfone. 4. The use of claim 1, wherein said triazine-based antiprotozoal drug is diclazuril. 5. The use of claim 1, wherein the protozoan infection is selected from the group consisting of sarcosporidiosis, pirplasmosis, babesiosis, toxoplasmosis and cryptosporidiosis. 6. The use of claim 1, wherein said protozoan infection is equine encephalomyelitis in equines, and said triazine-based antiprotozoal drug is diclazuril. 7. The purposes of claim 1, wherein said protozoal infection is equine encephalomyelitis or pyoplasmosis in equines, and said antiprotozoal drug based on triazine is sulfonyltoltrazuril or toltrazuril sulfone. 8. The use of claim 1, wherein the protozoal infection is equine encephalomyelitis or pyoplasmosis in equines, and the triazine-based antiprotozoal drug is diclazuril. 9. The use of claim 1, wherein the protozoal infection is human cryptosporidiosis.